/*
* Copyright (c) 2006-2007 Erin Catto http:
*
* This software is provided 'as-is', without any express or implied
* warranty.  In no event will the authors be held liable for any damages
* arising from the use of this software.
* Permission is granted to anyone to use this software for any purpose,
* including commercial applications, and to alter it and redistribute it
* freely, subject to the following restrictions:
* 1. The origin of this software must not be misrepresented; you must not
* claim that you wrote the original software. If you use this software
* in a product, an acknowledgment in the product documentation would be
* appreciated but is not required.
* 2. Altered source versions must be plainly marked, and must not be
* misrepresented the original software.
* 3. This notice may not be removed or altered from any source distribution.
*/

goog.provide('box2d.Distance');

goog.require('box2d.Math');

box2d.Distance.ProcessTwo = function(p1Out, p2Out, p1s, p2s, points) {
  // If in point[1] region
  //box2d.Vec2 r = -points[1];
  var rX = -points[1].x;
  var rY = -points[1].y;
  //box2d.Vec2 d = points[1] - points[0];
  var dX = points[0].x - points[1].x;
  var dY = points[0].y - points[1].y;
  //float32 length = d.Normalize();
  var length = Math.sqrt(dX * dX + dY * dY);
  dX /= length;
  dY /= length;

  //float32 lambda = b2Dot(r, d);
  var lambda = rX * dX + rY * dY;
  if (lambda <= 0.0 || length < Number.MIN_VALUE) {
    // The simplex is reduced to a point.
    //*p1Out = p1s[1];
    p1Out.SetV(p1s[1]);
    //*p2Out = p2s[1];
    p2Out.SetV(p2s[1]);
    //p1s[0] = p1s[1];
    p1s[0].SetV(p1s[1]);
    //p2s[0] = p2s[1];
    p2s[0].SetV(p2s[1]);
    points[0].SetV(points[1]);
    return 1;
  }

  // Else in edge region
  lambda /= length;
  //*p1Out = p1s[1] + lambda * (p1s[0] - p1s[1]);
  p1Out.x = p1s[1].x + lambda * (p1s[0].x - p1s[1].x);
  p1Out.y = p1s[1].y + lambda * (p1s[0].y - p1s[1].y);
  //*p2Out = p2s[1] + lambda * (p2s[0] - p2s[1]);
  p2Out.x = p2s[1].x + lambda * (p2s[0].x - p2s[1].x);
  p2Out.y = p2s[1].y + lambda * (p2s[0].y - p2s[1].y);
  return 2;
};
box2d.Distance.ProcessThree = function(p1Out, p2Out, p1s, p2s, points) {
  //box2d.Vec2 a = points[0];
  var aX = points[0].x;
  var aY = points[0].y;
  //box2d.Vec2 b = points[1];
  var bX = points[1].x;
  var bY = points[1].y;
  //box2d.Vec2 c = points[2];
  var cX = points[2].x;
  var cY = points[2].y;

  //box2d.Vec2 ab = b - a;
  var abX = bX - aX;
  var abY = bY - aY;
  //box2d.Vec2 ac = c - a;
  var acX = cX - aX;
  var acY = cY - aY;
  //box2d.Vec2 bc = c - b;
  var bcX = cX - bX;
  var bcY = cY - bY;

  //float32 sn = -b2Dot(a, ab), sd = b2Dot(b, ab);
  var sn = -(aX * abX + aY * abY);
  var sd = (bX * abX + bY * abY);
  //float32 tn = -b2Dot(a, ac), td = b2Dot(c, ac);
  var tn = -(aX * acX + aY * acY);
  var td = (cX * acX + cY * acY);
  //float32 un = -b2Dot(b, bc), ud = b2Dot(c, bc);
  var un = -(bX * bcX + bY * bcY);
  var ud = (cX * bcX + cY * bcY);

  // In vertex c region?
  if (td <= 0.0 && ud <= 0.0) {
    // Single point
    //*p1Out = p1s[2];
    p1Out.SetV(p1s[2]);
    //*p2Out = p2s[2];
    p2Out.SetV(p2s[2]);
    //p1s[0] = p1s[2];
    p1s[0].SetV(p1s[2]);
    //p2s[0] = p2s[2];
    p2s[0].SetV(p2s[2]);
    points[0].SetV(points[2]);
    return 1;
  }

  // Should not be in vertex a or b region.
  //box2d.Settings.b2Assert(sn > 0.0 || tn > 0.0);
  //box2d.Settings.b2Assert(sd > 0.0 || un > 0.0);
  //float32 n = b2Cross(ab, ac);
  var n = abX * acY - abY * acX;

  // Should not be in edge ab region.
  //float32 vc = n * b2Cross(a, b);
  var vc = n * (aX * bY - aY * bX);
  //box2d.Settings.b2Assert(vc > 0.0 || sn > 0.0 || sd > 0.0);
  // In edge bc region?
  //float32 va = n * b2Cross(b, c);
  var va = n * (bX * cY - bY * cX);
  var lambda;
  if (va <= 0.0 && un >= 0.0 && ud >= 0.0) {
    //box2d.Settings.b2Assert(un + ud > 0.0);
    //float32 lambda = un / (un + ud);
    lambda = un / (un + ud);
    //*p1Out = p1s[1] + lambda * (p1s[2] - p1s[1]);
    p1Out.x = p1s[1].x + lambda * (p1s[2].x - p1s[1].x);
    p1Out.y = p1s[1].y + lambda * (p1s[2].y - p1s[1].y);
    //*p2Out = p2s[1] + lambda * (p2s[2] - p2s[1]);
    p2Out.x = p2s[1].x + lambda * (p2s[2].x - p2s[1].x);
    p2Out.y = p2s[1].y + lambda * (p2s[2].y - p2s[1].y);
    //p1s[0] = p1s[2];
    p1s[0].SetV(p1s[2]);
    //p2s[0] = p2s[2];
    p2s[0].SetV(p2s[2]);
    //points[0] = points[2];
    points[0].SetV(points[2]);
    return 2;
  }

  // In edge ac region?
  //float32 vb = n * b2Cross(c, a);
  var vb = n * (cX * aY - cY * aX);
  if (vb <= 0.0 && tn >= 0.0 && td >= 0.0) {
    //box2d.Settings.b2Assert(tn + td > 0.0);
    //float32 lambda = tn / (tn + td);
    lambda = tn / (tn + td);
    //*p1Out = p1s[0] + lambda * (p1s[2] - p1s[0]);
    p1Out.x = p1s[0].x + lambda * (p1s[2].x - p1s[0].x);
    p1Out.y = p1s[0].y + lambda * (p1s[2].y - p1s[0].y);
    //*p2Out = p2s[0] + lambda * (p2s[2] - p2s[0]);
    p2Out.x = p2s[0].x + lambda * (p2s[2].x - p2s[0].x);
    p2Out.y = p2s[0].y + lambda * (p2s[2].y - p2s[0].y);
    //p1s[1] = p1s[2];
    p1s[1].SetV(p1s[2]);
    //p2s[1] = p2s[2];
    p2s[1].SetV(p2s[2]);
    //points[1] = points[2];
    points[1].SetV(points[2]);
    return 2;
  }

  // Inside the triangle, compute barycentric coordinates
  //float32 denom = va + vb + vc;
  var denom = va + vb + vc;
  //box2d.Settings.b2Assert(denom > 0.0);
  denom = 1.0 / denom;
  //float32 u = va * denom;
  var u = va * denom;
  //float32 v = vb * denom;
  var v = vb * denom;
  //float32 w = 1.0f - u - v;
  var w = 1.0 - u - v;
  //*p1Out = u * p1s[0] + v * p1s[1] + w * p1s[2];
  p1Out.x = u * p1s[0].x + v * p1s[1].x + w * p1s[2].x;
  p1Out.y = u * p1s[0].y + v * p1s[1].y + w * p1s[2].y;
  //*p2Out = u * p2s[0] + v * p2s[1] + w * p2s[2];
  p2Out.x = u * p2s[0].x + v * p2s[1].x + w * p2s[2].x;
  p2Out.y = u * p2s[0].y + v * p2s[1].y + w * p2s[2].y;
  return 3;
};
box2d.Distance.InPoinsts = function(w, points, pointCount) {
  for (var i = 0; i < pointCount; ++i) {
    if (w.x == points[i].x && w.y == points[i].y) {
      return true;
    }
  }

  return false;
};
box2d.Distance.Distance = function(p1Out, p2Out, shape1, shape2) {
  //box2d.Vec2 p1s[3], p2s[3];
  var p1s = new Array(3);
  var p2s = new Array(3);
  //box2d.Vec2 points[3];
  var points = new Array(3);
  //int32 pointCount = 0;
  var pointCount = 0;

  //*p1Out = shape1->m_position;
  p1Out.SetV(shape1.m_position);
  //*p2Out = shape2->m_position;
  p2Out.SetV(shape2.m_position);

  var vSqr = 0.0;
  var maxIterations = 20;
  for (var iter = 0; iter < maxIterations; ++iter) {
    //box2d.Vec2 v = *p2Out - *p1Out;
    var vX = p2Out.x - p1Out.x;
    var vY = p2Out.y - p1Out.y;
    //box2d.Vec2 w1 = shape1->Support(v);
    var w1 = shape1.Support(vX, vY);
    //box2d.Vec2 w2 = shape2->Support(-v);
    var w2 = shape2.Support(-vX, -vY);
    //float32 vSqr = b2Dot(v, v);
    vSqr = (vX * vX + vY * vY);
    //box2d.Vec2 w = w2 - w1;
    var wX = w2.x - w1.x;
    var wY = w2.y - w1.y;
    //float32 vw = b2Dot(v, w);
    var vw = (vX * wX + vY * wY);
    //if (vSqr - b2Dot(v, w) <= 0.01f * vSqr)
    if (vSqr - (vX * wX + vY * wY) <= 0.01 * vSqr) {
      if (pointCount == 0) {
        //*p1Out = w1;
        p1Out.SetV(w1);
        //*p2Out = w2;
        p2Out.SetV(w2);
      }
      box2d.Distance.g_GJK_Iterations = iter;
      return Math.sqrt(vSqr);
    }

    switch (pointCount) {
    case 0:
      //p1s[0] = w1;
      p1s[0].SetV(w1);
      //p2s[0] = w2;
      p2s[0].SetV(w2);
      points[0].x = wX;
      points[0].y = wY;
      //*p1Out = p1s[0];
      p1Out.SetV(p1s[0]);
      //*p2Out = p2s[0];
      p2Out.SetV(p2s[0]);
      ++pointCount;
      break;

    case 1:
      //p1s[1] = w1;
      p1s[1].SetV(w1);
      //p2s[1] = w2;
      p2s[1].SetV(w2);
      //points[1] = w;
      points[1].x = wX;
      points[1].y = wY;
      pointCount = box2d.Distance.ProcessTwo(p1Out, p2Out, p1s, p2s, points);
      break;

    case 2:
      //p1s[2] = w1;
      p1s[2].SetV(w1);
      //p2s[2] = w2;
      p2s[2].SetV(w2);
      //points[2] = w;
      points[2].x = wX;
      points[2].y = wY;
      pointCount = box2d.Distance.ProcessThree(p1Out, p2Out, p1s, p2s, points);
      break;
    }

    // If we have three points, then the origin is in the corresponding triangle.
    if (pointCount == 3) {
      box2d.Distance.g_GJK_Iterations = iter;
      return 0.0;
    }

    //float32 maxSqr = -FLT_MAX;
    var maxSqr = -Number.MAX_VALUE;
    for (var i = 0; i < pointCount; ++i) {
      //maxSqr = Math.max(maxSqr, b2Dot(points[i], points[i]));
      maxSqr = Math.max(maxSqr, (points[i].x * points[i].x + points[i].y * points[i].y));
    }

    if (pointCount == 3 || vSqr <= 100.0 * Number.MIN_VALUE * maxSqr) {
      box2d.Distance.g_GJK_Iterations = iter;
      return Math.sqrt(vSqr);
    }
  }

  box2d.Distance.g_GJK_Iterations = maxIterations;
  return Math.sqrt(vSqr);
};
box2d.Distance.g_GJK_Iterations = 0;
